Chapter 22 - Inheritance

Fetal testing

Fetal testing

________ is recommended for older mothers to check for Down syndrome in the embryo.

IO

________ is recessive to both IA and IB, while IA and IB are codominant when paired together.

IAIB genotype

For ________, both antigen A and antigen B are expressed since each of the alleles produces its own antigen.

Phenotype

an observable characteristic of an organism.

sexual reproduction

Each organism inherits one allele from the mother and one allele from the father during ________.

DNA

The part of chromosome, which contains genetic information used in the development and functioning of all organisms.

Down syndrome

a condition caused by a chromosome mutation during meiosis (gamete production)

Co dominance

The state when both alleles contribute equally to the phenotype.

Mutation

a change in gene or chromosomal structure.

Hereditary factors

________ are responsible for transmission of characteristics from one generation to the next.

human blood groups

The gene for ________ is said to have multiple alleles since it exists in more than two alleles.

single amino

It causes a(n) ________ acid in the normal haemoglobin chain to be replaced by another amino acid.

HbS molecules

________ clump together under low oxygen concentration, causing red blood cells to become sickle- shaped.

body cells

The zygote inherits 3 copies of chromosome 21 instead of 2, and this mutation is present in all ________ due to mitosis during zygote development.

surface of red blood cells

The gene for blood group codes for a protein present on the ________, called an antigen.

Mutagens

________ are physical or chemical agents that increase the rate of mutation.

allele IA

The ________ codes for antigen A, IB codes for antigen B, and no antigen is expressed for allele IO.

Mutations

________ can also be caused by exposure to mutagens.

Human blood groups

Characteristics determined by 3 alleles for 1 gene: IA, IB and IO.

Gene

a DNA segment located in a chromosome, which codes for a single unit of inheritance.

Allele

different versions of the same gene.

Genotype

The genetic make-up of an organism.

dominant allele

the allele that is fully expressed in the phenotype under both homozygous and heterozygous conditions.

Recessive allele

the allele that is only expressed in the phenotype under the homozygous condition.

Complete dominance

when the heterozygote has the same phenotype as the dominant homozygote.

Mutation

a change in gene or chromosomal structure.

Sickle cell anaemia

a blood disorder where red blood cells possess a rigid, sickle shape when oxygen concentration in the blood is low.

Natural Selection

Selection occurs when natural environmental conditions change

Artificial selection

Selection where humans select the varieties of organism that suit their need